Japanese hedge parsley is a biennial herb that grows 2 – 4 feet tall when flowering in its second year of growth. First-year rosettes are low, parsley-like and green until fall. Leaves are alternate, fern-like, 2 – 5 inches long and slightly hairy. Japanese hedge parsley flowers are white in multiple broad domed umbels. The flower petals are uneven, petals on the outside of the inflorescence are often larger than on the inside. Fruit are small and covered with coarse hairs and reddish purple splotching. Japanese hedge parsley threatens woodlands and savannas. Hedge parsley (T. arvensis) is very similar and invasive.
In 100 Years of Change in the Distribution of Common Indiana Weeds by William and Edith Overlease (2002) reported that Japanese hedge parsley was not found in Indiana in 1899 (Coulter’s Catalogue of Indiana Plants). However in 1940 (Deam’s Flora), Japanese hedge parsley but could be found in Jefferson, Montgomery and Switzerland counties. Deam noted that Japanese hedge parsley was “common on a wooded bank 3 miles north of Crawfordsville in 1926. In 1936 it was discovered by Miss Edna Bamta along the river bluff between Brooksburg and Madison in Jefferson County.” In 2002, Overlease reported Japanese hedge parsley in roadsides and often along railroad tracks in the following Indiana counties: the following 16 counties in 2002: Bartholomew, Dearborn, Henry, Howard, Jefferson, Johnson, Knox, Montgomery, Noble, Orange, Pike, Posey, Ripley, Tippecanoe, Vermillion, and Vigo.